Blood transfusion is the intravenous administration of blood components (most commonly packed red blood cells [PRBCs]) to restore oxygen-carrying capacity, improve tissue perfusion, or correct significant hematologic deficits.

Transfusion therapy may be:

1. Simple (Top-Up) TransfusionAdministration of PRBCs without removal of the patient’s blood.

2. Exchange Blood Transfusion (EBT)Simultaneous removal of patient blood and replacement with donor PRBCs to reduce pathological hemoglobin (e.g., HbS in sickle cell disease).

1. Simple (Top-Up) Blood Transfusion

Indications

Simple transfusion is indicated when there is:

• Symptomatic anemia, including:

  • Dyspnea

  • Tachycardia

  • Severe weakness

  • Signs of cardiac compromise

• Hemoglobin (Hb) < 6 g/dL

• Acute drop in Hb by > 2 g/dL below steady-state value

• Acute blood loss

• Perioperative optimization (case-dependent)

• Severe aplastic crisis

Important Clinical Note (Sickle Cell Disease)

In steady-state sickle cell disease (SCD), transfusion is not routinely indicated solely because Hb is 8–10 g/dL, as chronic anemia is physiologically compensated. Unnecessary transfusion increases the risk of:

• Hyperviscosity

• Alloimmunization

• Iron overload

Dosage and Administration

• PRBC dose (children): 10–15 mL/kg over 3–4 hours

• Expected Hb rise: ~1 g/dL per 10 mL/kg PRBC

• Reassess Hb 4–6 hours post-transfusion

Monitoring During Transfusion

• Baseline vitals

• 15 minutes after starting

• Hourly monitoring

• Post-transfusion observation

Exchange Blood Transfusion (EBT)

Exchange transfusion reduces the proportion of abnormal red cells (e.g., HbS) and replaces them with normal HbA-containing cells.

Goal in Sickle Cell Disease

• Reduce HbS concentration to < 30%

• Improve oxygen delivery

• Reduce blood viscosity

• Prevent further sickling

EBT can be performed:

• Manually

• Automated red cell apheresis

Indications for Exchange Blood Transfusion

Absolute Indications

• Cerebrovascular accident (stroke)

• Acute chest syndrome (moderate–severe)

• Multi-organ failure

• Systemic marrow fat embolism

• Pre-operative management for high-risk surgery

• Prevention of recurrent stroke

Relative Indications

• Recurrent severe vaso-occlusive crises

• Intractable priapism

• Severe pregnancy complications in SCD

Risk Factors for Transfusion Requirement

• Severe anemia

• Hemoglobinopathies (e.g., SCD, thalassemia)

• Bone marrow failure

• Major surgery

• Trauma

• Obstetric hemorrhage

• Chronic kidney disease

Signs and Symptoms Requiring Urgent Transfusion

• Severe pallor

• Hypotension

• Syncope

• Altered mental status

• Hypoxia

• Signs of cardiac failure

Diagnostic Criteria for Transfusion Decision

Transfusion is based on:

• Hemoglobin level

• Hemodynamic status

• Oxygen delivery compromise

• Underlying diagnosis

• Rate of Hb decline

Transfusion should not rely solely on laboratory value but must be clinically indicated.

Investigations Before Transfusion

1. Complete blood count (CBC)

2. Blood grouping and crossmatch

3. Antibody screen

4. Reticulocyte count

5. Renal and liver function (if indicated)

6. Hb electrophoresis (in SCD for exchange transfusion planning)

Treatment

Non-Pharmacological

• Oxygen therapy (if hypoxic)

• Adequate hydration

• Treat underlying cause (infection, bleeding, crisis)

• Careful fluid balance monitoring

Pharmacological

• Diuretics (e.g., furosemide) in patients at risk of volume overload

• Iron chelation therapy (in chronic transfusion therapy)

  • Deferoxamine

  • Deferasirox

• Analgesics in SCD crisis

• Antibiotics if infection present

Complications of Blood Transfusion

Acute Complications

• Acute hemolytic transfusion reaction

• Febrile non-hemolytic reaction

• Allergic reactions

• Anaphylaxis

• Transfusion-associated circulatory overload (TACO)

• Transfusion-related acute lung injury (TRALI)

• Sepsis

Delayed Complications

• Alloimmunization

• Iron overload

• Delayed hemolytic reaction

• Transmission of infections (rare with screening)

Prevention Strategies

• Strict adherence to transfusion guidelines

• Leukoreduced blood products

• Extended antigen matching in SCD

• Iron overload monitoring (serum ferritin, MRI liver iron)

• Vaccination in chronically transfused patients

• Use of standardized treatment guidelines (STG)